Steve Mould
3 HN recommenders · recommended in 3 months, 2021–2022
18:32 · 1.7M views · Aug 1, 2020
Steve Mould explains homochirality: why biological molecules like sugars and amino acids come in only one handedness. He covers ideas about how this asymmetry might have arisen, touching on meteorite samples and RNA.
Cited as a clear, accessible explanation of why life uses only one version of chiral molecules.
3 comments from Hacker News
Can anyone comment on how producers could be isolating the the 'd' enantiomer? Are they using enzymes? Steve Mould has a great video [1] on homochirality in nature and says, "Why are all the sugar molecules that you buy from the shops right-handed? ... If you were to make some sugar for yourself in a chemistry lab by mixing some chemicals together, you would get a 50/50 mix of left-handed sugar and right-handed sugar." He goes on to describe how enzymes in nature exclusively make homochiral molecules, and since all our sugar is made by enzymes, all our sugar is homochiral. Later in the video he describes how you can filter enantiomers by finding an enzyme in nature that 'eats' the undesired enantiomer, finding the DNA for it, and coercing bacteria into producing that enzyme. This seems quite complicated and potentially out of reach for a clandestine drug-making operation. Is there another way? [1] this video
Here is a video talking about molecular chirality and how nature really only produces one version of molecules this video . If it picked up the molecules in the atmosphere those atmospheric molecules should have been made by life on earth and those have a handedness bias depending on the molecule, some are produced right handed only or left handed only because they are made one atom at a time and need to be one handed for life to use them. Abiotic synthesis produces a 50/50 bias of left and right handed molecules because they are made all at once.
Your question reminded me of this video about "Homochirality: Why Nature Never Makes Mirror Molecules"[1] - even though it's not directly related I think it may be interesting to you. [1] this video